The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.
File transmission techniques are classified into a server-client model and a P2P (Peer to Peer) model.
The inventor(s) has noted that in the file transmission technique based on a server-client model, a server stores and transmits a file, whereas a client receives and uses the file. All clients are required to access the server so as to receive a desired file from the server. Therefore, the inventor(s) has noted that when a large number of clients access at the same time, a bottleneck phenomenon is caused at the server and the network.
On the contrary, in the file transmission technique based on P2P, a number of user devices perform simultaneously the functions of client and server by transmitting or receiving a file to or from each other. The inventor(s) has experienced that this technique can solve a bottleneck issue at the server and the network. The inventor(s) has noted that in P2P communication technique, user devices selectively performing the functions of client and server at the same layer depending on situations are referred to as peer.
However, the inventor(s) has noted that in typical P2P-based file transmission, resources are shared by all user devices that participate in P2P communication. Therefore, the inventor(s) has experienced that as the number of user device participants increases, traffic is also increasing in the communication network. The inventor(s) has experienced that this causes a system load at the user device and also invites variation of transmission rate depending on the specifications of the user device.
The inventor(s) has noted that for this reason, P2P-based file-distributed transmission technique has been introduced. In this technique, a file is divided into small-sized fragments, which are distributed to a number of peers and stored. Then the file is transmitted in parallel through such peers. Representatively, BitTorrent is known in the art.
For this P2P-based file-distributed transmission, a peer management server (such as Tracker of BitTorrent) that manages information about peers sharing at least part of a file with each other is additionally needed. A client that desires to receive a file should access the peer management server, receive a list of peers sharing the desired file, establish respective sessions with such peers in the received peer list, and receive a lot of fragments of the file in parallel.
By the way, in this P2P-based file-distributed transmission technique, when there is a client's request for a peer list with regard to a specific file, the peer management server randomly selects a predetermined number (e.g., fifty) of peers from among many peers sharing the specific file without considering a client's communication environment. Therefore, the inventor(s) has experienced that a communication operator suffers unnecessary increases of traffic in the IX (Internet eXchange) interworking network and has difficulty in traffic engineering of IX interworking point.